Momentum free bearing for use in prosthetic and orthotic devices

ABSTRACT

A momentum free bearing assembly for use in orthotic and prosthetic devices and a prosthetic knee incorporating the same are disclosed. The bearing assembly includes an engaging ring having a swivel portion received within the engaging ring. The engaging ring is received within a bore in a mount. Retainer rings may be placed on either side of the engaging ring within the bore to retain the engaging ring within the mount. Seals having sealing members may be provided on either side of the engaging ring to seal the engaging ring within the mount. A cylindrical rod engages the swivel portion and the seal through bores provided in each of the seal and the swivel portion. The ends of the cylindrical rod can be press-fit within bores on a mount and a frame of a prosthetic knee.

This application is a continuation of U.S. application Ser. No.11/896,960, filed Sep. 7, 2007, which claims the benefit of U.S.Provisional Application No. 60/845,503, filed Sep. 19, 2006. Theentirety of each of these applications is incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to the field prosthetic andorthotic devices, and more particularly to a momentum free bearingassembly for use as a joint connection in prosthetic and orthoticdevices.

BACKGROUND

Bearing assemblies in orthotic devices and prosthetic limbs, such asprosthetic knees, traditionally allow one degree-of-freedom of movementbetween joint connections. That is, the bearings allow the connectionsto rotate about a single axis, while limiting the movement of theconnections in all other directions. Examples of prosthetic limbs usingconventional single degree-of-freedom bearing assemblies are describedin U.S. Pat. No. 5,092,902 (Adams et al.), U.S. Pat. No. 5,376,137(Shorter et al.), U.S. Pat. No. 5,443,521 (Knoth et al.), and U.S. Pat.No. 5,895,430 (O'Conner) all herein incorporated by reference.

The conventional single degree-of-freedom bearing assemblies have thedisadvantage of transferring torsional loads to the linkages of thejoint connection. In a common prosthetic knee, torsional loading canoccur during the stance phase of the gait cycle, which involves a userplanting his foot. In particular, torsional loads can arise when aperson using a prosthetic knee plants the foot associated with theprosthetic knee, and rotates their torso and other leg in order toaccomplish a turn. During this turn the prosthetic knee will seetorsional loading.

Because of the transfer of torsional loading between the linkages, thelinkages must be designed to withstand the torsional forces that buildupwithin the linkages. This typically entails providing a linkage that hasa larger diameter or cross-sectional area.

Such larger linkages can add substantially to the weight of a prostheticdevice especially for example in prosthetic knees that are mechanicallycomplex and employ a plurality of hinge or rotation points that allowvariations in the action of the knee throughout the gait cycle. Anexample of one such prosthetic joint is disclosed in the Shorter et al.patent.

Additionally, for prosthetic limbs having a control unit such as ahydraulic cylinder, the transferred torsional loads can cause bindingbetween the piston and cylinder. This can lead to the prosthetic limbperforming in an unexpected manner and possibly damaging the piston andcylinder, which are expensive to replace.

It would thus be beneficial to provide a joint connection thateliminates or reduces the torsional loads transferred to the linkages ofan orthotic or prosthetic device. Such a connection would isolatecomplex or expensive components from torsional loading, and subject themto axial loading only.

The present invention provides just such a connection by providing amomentum free connection between linkages, and thus effectivelyisolating the linkages from torsional loading, as described below.

SUMMARY

In order to provide an improved connection for an orthotic or aprosthetic limb, a momentum free bearing assembly for use as a jointconnection in orthotic or prosthetic devices is described. The momentumfree bearing assembly of this disclosure provides the ability formovement between linkages in three degrees-of-freedom, allowing for somerotation between the linkages about three axes, instead of just one.

Most orthotic or prosthetic devices, such as prosthetic knees, aresubject to torsional loading. Use of the momentum free bearing of thisdisclosure in orthotic and prosthetic devices can isolate some of themore complex components of an orthotic or prosthetic device fromtorsional loading.

This isolation of the complex components can allow for a linkage orcontrol unit of an orthotic or prosthetic device to be subject to anaxial load only, while the less complex and easier to manufacturebearing assemblies eliminate the torsional loading from the linkage orcontrol unit. This prevents undue stress in the complex component.

This elimination or reduction in torsional loading of a linkage providesnumerous benefits. For example, a linkage can have a reduced diameter orcross-sectional area since it will not be required to carry torsionalloads. A reduced diameter or cross-sectional area linkage can provideweight savings, which is very important in the field of orthotic devicesand prosthetic limbs, since it is more difficult and requires moreenergy for a person to utilize heavier orthotics and prosthetic limbsthan lighter orthotics and prosthetic limbs.

Another advantage can be realized when a prosthetic limb uses a controlunit such as a hydraulic piston type control unit. These control unitsare well known in the art, some examples are disclosed in the Adams etal. Shorter et al. and Knoth et al. patents. The bearing assembly ofthis disclosure can be used with any of the currently known or anyfuture developed control units. These control units can also be madelighter and smaller if they are not subjected to torsional loading. Inaddition, the elimination of torsional loading reduces the risk that apiston could bind and catch in a cylinder, thus reducing the possibilitythat the prosthetic limb would behave in a manner that is unexpected bythe user, and reducing the risk of damage to the expensive components ofthe control unit.

The reduction or elimination of torsional loading of a linkage, oractive or passive control unit also provides the benefit of reduced wearon the more expensive components of the orthotic device or theprosthetic limb, while shifting the loads to more durable and possiblyless expensive components.

Because the bearing assemblies according to this disclosure allow forrotation about three axes, little or no torsional loads are transmittedbetween the components that are connected through the bearingassemblies. Instead, the frame of an orthotic device or a prostheticjoint utilizing bearing assemblies in accordance with this disclosuresupport most or all of the torsional loading that may arise during theuse of such an orthotic device or a prosthetic limb.

The momentum free bearing assembly of the disclosure isolates thelinkages of a joint connection in orthotic and prosthetic devices fromtorsional loading from a frame through the following structuralconfiguration. The bearing assembly has an engaging ring for receiving aswivel portion that is configured to swivel within the engaging ring inthree directions. The bearing assembly further includes a cylindricalrod that is configured to engage a bore within the swivel portion toallow the rod to rotate in three degrees-of-freedom with respect to theengaging ring. The engaging ring is configured to engage a portion ofthe linkage and each end of the cylindrical rod is configured to engagethe frame in a fixed manner, so that the linkage is isolated fromtorsional loading and can rotate in three degrees-of-freedom withrespect to the frame.

The linkage may have a mount that is configured to receive the engagingring in a fixed manner within a bore inside the mount. The bearingassembly further comprises a plurality of retaining rings that areconfigured to be received within the bore of the mount on either side ofthe engaging ring in order to retain the engaging ring within the boreof the mount. The mount may include an extending portion that allows themount to be removably connected to a linkage, or to an active or passivecontrol unit.

The bearing assembly may include a plurality of seals. The plurality ofseals of the bearing assembly are configured to engage the mount in asealing manner in order to seal the retaining rings and the engagingring within the mount.

The plurality of seals each may have receiving portions that areconfigured to receive sealing members. The sealing members can beresilient sealing members such as conventional O-rings, gaskets, orsealing compounds such as RTV silicones.

The bearing assembly can be used as a joint connection within anorthotic device or a prosthetic limb, such as a prosthetic elbow, hip,ankle or knee joint. An orthotic or prosthetic joint may comprise aframe having proximal and distal portions and a first proximal mountengaging the proximal portion of the frame in a pivotal manner. Theorthotic or prosthetic joint also has a linkage having proximal anddistal portions, which can be a simple mechanical linkage or a morecomplex active or passive control unit. The linkage has a first pivotconnection between the proximal portion of the linkage and the firstproximal mount and a second pivot connection between the distal portionof the linkage and a distal portion of the frame. The first and secondpivot connections may include some or all of the features of the bearingassembly described above.

The first proximal mount may have a plurality of flange portions. Eachof the flange portions may include a bore for receiving a cylindricalrod of a bearing assembly of the first pivotal connection in a fixedmanner, such that the linkage can rotate with respect to the firstproximal mount.

The frame of the orthotic or prosthetic joint may have bores at a distalportion thereof for receiving a cylindrical rod of a bearing assembly ofthe second pivotal connection in a fixed manner, such that the linkagerotates in three directions with respect to the frame.

The orthotic or prosthetic joint may include bores in the first proximalmount and in the distal portion of the frame for receiving cylindricalrods of bearing assemblies, such that the linkage can rotate in threedirections with respect to both the first proximal mount and the frame,respectively.

The numerous advantages, features and function of the momentum freebearing assembly and a prosthetic limb incorporating the bearingassembly will become readily apparent and better understood in view ofthe following description, appended claims, and accompanying drawings.The following description is not intended to limit the environments inwhich the momentum free bearing assembly may be used, but instead merelyprovides exemplary embodiments for ease of understanding.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a generalized perspective view of a prosthetic kneeincorporating momentum free bearing assemblies.

FIG. 2 is a close up sectional view of the proximal bearing assemblyshown in FIG. 1.

FIG. 3 is a close up sectional view of the distal bearing assembly shownin FIG. 1.

FIG. 4 is a perspective view of the second mount or proximal connectionassembly shown in FIG. 1.

FIG. 5 is an exploded perspective view of the components of the bearingassemblies shown in FIG. 1.

FIG. 6 is a perspective view of a swivel portion received within anengaging portion of a bearing assembly as shown in FIG. 1.

FIG. 7 is a perspective view of a seal of a bearing assembly as shown inFIG. 1.

FIG. 8 is a perspective view of a retainer ring of a bearing assembly asshown in FIG. 1.

The features in the drawing figures are generalized and not shown toscale, so that the features thereof may be more clearly demonstrated.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS A. Environment and Contextof the Various Embodiments

Orthotic and prosthetic devices can include mechanically simpleconnections allowing for a relatively simple movement of the supportedbody part or prosthetic device. They can also include mechanicallycomplex hinges and connections that allow the orthotic or prostheticdevice to reproduce a complex range of motions.

Due to the complexity of the motions of body parts supported by orthoticdevices and prosthetic devices that reproduce the movements of bodyparts, these devices are typically subject to torsional loading. Themomentum free bearing as disclosed can be used in any application whereit is beneficial to eliminate torsional loads and to transmit an axialload only. Such environments could include orthotic devices such as hip,knee, elbow, leg, arm, back or any type of brace or other orthoticdevice as well as any type of prosthetic device such as prostheticlimbs, including foot, elbow and hip joints.

For further ease of understanding the momentum free bearing assembly andthe use of a momentum free bearing assembly in a prosthetic knee jointas disclosed herein, a description of a few terms is necessary. As usedherein, the term “proximal” has its ordinary meaning and refers to alocation that is closer to the heart than another location. Likewise,the term “distal” has its ordinary meaning and refers to a location thatis further from the heart than another location. The term “posterior”also has its ordinary meaning and refers to a location that is behind orto the rear of another location. Lastly, the term “anterior” has itsordinary meaning and refers to a location that is ahead or to the frontof another location.

B. Detailed Description of a First Embodiment

The momentum free bearing assembly of this disclosure is described foruse in a prosthetic knee for ease of understanding. This description isnot intended to be limiting; on the contrary, the momentum free bearingassembly can be used in any appropriate orthotic or prosthetic device.

In one exemplary use, a first embodiment of a prosthetic knee includingmomentum free bearing assemblies is shown in FIG. 1. The prosthetic knee100 includes a frame 110 that supports the structure of the prostheticknee 100, as well as transmits a portion of the weight of a user's bodyto any type of known prosthetic foot (not shown), which may be aestheticor utilitarian in design. The prosthetic knee joint 100 is connected toany type of known socket for receiving a residuum (not shown) at aproximal end through any conventional connection such as a pyramidconnection. Some examples of conventional pyramid connections are partnumbers A-135100, A-235300, A-335100, and A-435120 all available fromÖssur hf., Reykjavik, Iceland. As already mentioned, the prosthetic knee100 is also connected to a prosthetic foot through any conventionalconnection such as a pyramid connection.

The prosthetic knee 100 includes a proximal mount assembly 200, whichcan be seen in cross section in FIG. 2. The proximal mount assembly 200is configured in any appropriate manner to be pivotally connected to theframe 110 of the prosthetic knee 100 at the pivot location 120. Forexample, the proximal mount assembly can be configured to have boresthat receive pivot rods so that the proximal mount assembly 200 maypivot with respect to the frame 110.

The specific details of the pivot structure 120 may be those known inthe art, for example pivot structures available as part numbersFRM61721U, MAK01501, MAK01502, FRM61524, MAK01503, FRM31522, andFRM61523, all available from Össur hf., Reykjavik, Iceland. Onerequirement of any pivot structure is that the proximal mount assembly200 should be able to pivot with respect to the frame 110. Of course,other configurations will be apparent to those of ordinary skill in theart of prosthetic knees.

The proximal mount assembly 200 may also be configured to receive aconventional pyramid coupling connection 250, as discussed above.However, any suitable conventional coupling mechanism, such as clamps orthreaded mounts may be used.

The proximal mount assembly 200 may include a filler 210 or guard thatis used to protect the proximal mount assembly 200 and the frame 110.The filler 210 may also protect the clothing of a user from becomingdamaged. The filler 210 can be made of any appropriate material,including hard and soft plastics, and is an optional component of theprosthetic knee 100.

The proximal mount assembly 200 may also include a plurality of flangeportions 240 located at a posterior portion 242 of the proximal mountassembly 200. The flanges can define a cut-out or recessed portion 230.Each flange portion 240 can also include a bore 220 therethrough.

The bores 220 in the flanges 240 are configured to receive a cylindricalrod 310 that forms the basis for a proximal connection assembly 300, asseen in FIG. 4. The proximal connection assembly 300 consists of amember having a bore 320 for receiving the components of a proximalbearing assembly 400.

The proximal connection assembly 300 may also include an extendingportion 302, as shown in FIG. 2, that can be used to connect to alinkage or a control unit 500 in any conventional manner, such as a bore304 in the extending portion that receives a connecting pin 350. Thespecific structure of how the proximal connection assembly 300 isconnected to a linkage or control unit 500 may be any connection knownto one of ordinary skill in the art, such as threaded connections,press-fitting or welding.

In an alternative construction, the proximal connection assembly 300 maynot have the extending portion 302, but instead may be connecteddirectly to the linkage or control unit 500. Such a connection may beaccomplished in any suitable manner known to those having ordinary skillin the art of orthotic and prosthetic devices.

The proximal connection assembly 300 is configured to receive theproximal bearing assembly 400. The proximal bearing assembly 400, seenin FIG. 5 in an exploded view, consists of a number of components thatare received within the bore 320 of the proximal connection assembly300.

The proximal bearing assembly 400 includes a bearing portion 420 that iscomposed of a swivel portion 424 that is received within an engagingring 422, as can be seen in FIG. 6. The swivel portion 424 is able toswivel within the engaging ring 422 in multiple axes. The swivel portion424 includes a bore 426 for receiving the cylindrical rod 310 therein.

The cylindrical rod 310 may be received within the bore 426 in a nearpress-fit manner, or simply in a machine-fit manner. Due to variationsin machining tolerances, the cylindrical rod 310 may easily slide withinthe bore 426, or the cylindrical rod 310 may engage the bore 426 in africtional manner.

The engaging ring 422 is received within the bore 320 of the proximalconnection assembly 300, as can best be seen in FIG. 2. The engagingring 422 may be machined to fit within the bore 320 with a machine-fit,and may also be adhesively retained within the bore 320 using any knownappropriate conventional adhesive.

The bore 320 may include grooves or receiving portions 306 that arepositioned to be located on either side of the engaging ring 422. Thereceiving portions 306 are configured to receive retaining rings 410,shown in FIG. 8, which are placed on either side of the engaging ring422 to maintain the engaging ring 422 within the bore 320, as can beseen in FIG. 2.

The proximal bearing assembly 400 may also include a plurality of seals430. Each seal includes receiving portions 432 configured to receivesealing members 434. One sealing member 434 may be located around thecircumference of the seal 430, as shown in FIG. 7, in order to providean air and fluid tight seal between the seal 430 and the bore 320 as canbe seen in FIG. 2. Another sealing member 434 can be provided around aside of the seal 430, as shown in FIG. 7, in order to provide an air andfluid tight seal between the seal 430 and the flange 240 as can be seenin FIG. 2. The seal members 434 may be conventional O-rings or gaskets,or any other suitable sealing structure.

One of each of the seals 430 can be provided on either side of theengaging ring 422 and in contact with the swivel portion, as shown inFIG. 2. The space between the engaging ring 422 and either seal 430 maybe packed with grease, or any other suitable lubricant. In this manner,the swivel portion 424 is provided with lubrication between the swivelportion 424 and the engaging ring 422. Thus, the swivel portion 424 mayfreely swivel within the engaging ring 422 in order to prevent torsionalloads from being transmitted through to the proximal connection assembly300.

The seals 430 also have bores 436 that may be configured to be press-fitonto the cylindrical rod 310, or alternatively the bores 436 could havea clearance-fit, or a machine-fit. Even if the bores 436 have only aclearance-fit, the grease or lubricant that is packed within the spacebetween the seals 430 and the engaging ring 422 is retained due to thesealing member 430 on the side of the seals 430 that engages the flanges240.

As shown in FIG. 2, the cylindrical rod 310 engages the flanges 240, theseals 430, and the swivel portion 424 of the bearing assembly 400. Thecylindrical rod 310 is press fit at both ends into either of the bores220 of the flange portions 240. With this configuration, the proximalconnection assembly 300 can rotate freely about the cylindrical rod 310in all three axes for at least a predetermined amount of rotation. Thus,the proximal connection assembly 300 transmits only an axial load to thelinkage or control unit 500. This allows any linkage or control unit tohave a reduced size, since they are not required to be capable ofwithstanding torsional forces. In addition, there is reduced risk ofbinding for a control unit.

In the exemplary embodiment, shown in FIGS. 1-3, the prosthetic knee 100includes a control unit 500. A control unit that is active or passive,as is well known in the art of prosthetic knees, may be provided.Exemplary control units may be used such as control units having thepart numbers SNJ01800U, and SNJ01800LU, both available from Össur hf.,Reykjavik, Iceland. However, a control unit is not necessary, andinstead a simple mechanical linkage could be provided. In either case,the proximal end 520 may include a linkage or piston rod 510 and thedistal end 530 may define the distal connection assembly 700.

The distal connection assembly 700, which can best be seen in FIG. 3, isof a similar design as the proximal connection assembly and includes acylindrical rod 710 and a bore 720 therethrough. The distal connectionassembly can include grooves or receiving portions similar to grooves orreceiving portions 306 for receiving retaining rings 610, which areidentical to retaining rings 410.

In the embodiment shown in FIGS. 1-3 the distal connection assembly isshown as being integral with the control unit 500. Of course, manyalternative constructions will be readily apparent to those havingordinary skill in the art of orthotic and prosthetic devices.

The bore 720 of the distal connection assembly 700 is configured toreceive a distal bearing assembly 600 that is identical in constructionto the proximal bearing assembly 400. The distal bearing assembly 600includes a bearing portion 620 that includes an engaging ring 622 and aswivel portion 624 having a bore 626 therethrough and such that theswivel portion 624 and the engaging ring 622 are configured to engageeach other in a swivel fashion, as previously described.

The distal bearing assembly 600 also includes a plurality of seals 630having bores 636 therethrough and receiving portions 632 for receivingsealing members 634 in an identical manner to the seals 430 discussedabove.

The distal mounting assembly 800 shown in FIG. 3 consists of bores 820passing through a distal portion of the frame 110 of the prosthetic knee100. The cylindrical rod 710 can be press-fit into the bores 820 of theframe 110, in a manner similar to that discussed above with respect tothe cylindrical rod 310 of the proximal connection assembly 300. In theexemplary embodiment shown in FIG. 3, there are protective plugs 830received within the bores 820 of the frame 110. These plugs are not anecessary component, but can serve as an aesthetic component and to keepdirt and debris from accumulating within the bores 820.

The distal bearing assembly 600 and the distal connection assembly 700function in exactly the same manner as discussed above with respect tothe proximal bearing assembly 400 and the proximal connection assembly300. That is, torsional forces are not transmitted through the distalconnection assembly 700 to the linkage or control unit 500, due to theswivel function of the distal bearing assembly 600.

In use, the prosthetic knee 100 functions in a manner known to thosehaving ordinary skill in the art of prosthetic knees. The frame 110 andthe proximal mount assembly 200 rotate with respect to each other tosimulate the motion and function of the human knee joint. Duringeveryday use of a prosthetic knee, the prosthetic knee will be subjectto both axial and torsional loading. The momentum free bearingsdescribed herein allow certain components of the prosthetic knee to beisolated from torsional loading.

In this manner, with both a proximal momentum free bearing assembly anda distal momentum free bearing assembly, a linkage or control unit issubject only to an axial loading along its length. As previouslydiscussed, the size of a linkage or control unit may be reduced, and theoverall weight of the prosthetic limb may be reduced, as a result of theuse of a proximal momentum free bearing assembly and a distal momentumfree bearing assembly.

Additionally, if any type of hydraulic control unit is used, there is areduced possibility of binding between the piston and cylinder of thecontrol unit, since neither the piston nor the control unit see atorsional load. Thus, the load is transmitted axially through and withinthe piston head and cylinder, in the manner that hydraulic cylinders aredesigned. This also applies to pneumatic pistons and cylinders as wellas any other known type of control unit.

C. Alternate Embodiments

While the momentum free bearings are shown in use in a prosthetic kneehaving a control unit, many alternative uses and embodiments will bereadily apparent to those having ordinary skill in the art of orthoticand prosthetic devices.

For example, the momentum free bearings can be utilized without theseals described, or with alternatively constructed seals. Suchalternative seals could include replacing the structure of the sealsdescribed herein with a gasket material, or with a seal having only sealmembers along one surface.

In other alternatives, the momentum free bearings can be used inorthotic devices such as braces for the knee or elbow. Also, themomentum free bearings may be used in orthotic devices designed tosupport any part of the body.

Further, the momentum free bearings may be used in any prosthetic devicesuch as prosthetic elbow, hip or ankle joints. The momentum freebearings can be used in any type of prosthetic device where it isdesired to isolate components of the prosthetic limb from torsionalloading.

The components of the momentum free bearings can be constructed from anysuitable materials, for example any suitable lightweight structuralmaterials such as stainless steels, aluminums, plastics, or any suitablecombinations thereof. The components of the prosthetic knee can be madefrom any suitable known materials, such as stainless steel, aluminum,plastic, carbon fiber or glass fiber composites or any suitablecombinations thereof.

Of course, it is to be understood that not necessarily all such objectsor advantages may be achieved in accordance with any particularembodiment of the invention. Thus, for example, those skilled in the artwill recognize that the invention may be embodied or carried out in amanner that achieves or optimizes one advantage or group of advantagesas taught herein without necessarily achieving other objects oradvantages as may be taught or suggested herein.

The skilled artisan will recognize the interchangeability of variousfeatures from different embodiments and method steps. In addition to thevariations described herein, other known equivalents for each featurecan be mixed and matched by one of ordinary skill in this art toconstruct a momentum free bearing for use in prosthetic limbs inaccordance with principles of the present invention.

Although this invention has been disclosed in the context of certainexemplary embodiments and examples, it therefore will be understood bythose skilled in the art that the present invention extends beyond thespecifically disclosed embodiments to other alternative embodimentsand/or uses of the invention and obvious modifications and equivalentsthereof. Thus, it is intended that the scope of the present inventionherein disclosed should not be limited by the particular disclosedembodiments described above, but should be determined only by a fairreading of the claims below.

1. An orthotic or prosthetic joint comprising: a frame having proximaland distal portions; a first proximal mount pivotally engaging theframe; and a linkage having proximal and distal portions, and a firstpivotal connection to the first proximal mount at the proximal portionthereof, and the linkage having a second pivotal connection to a distalportion of the frame at the distal portion thereof such that the linkageis free from torsional loading and rotates with three degrees-of-freedomwith respect to the frame; wherein the first and second pivotalconnections of the linkage each include a bearing assembly having: anengaging ring; a swivel portion defining a bore and received within theengaging ring so as to freely rotate in at least three directions; and acylindrical rod engaging the bore within the swivel portion; wherein theengaging ring of the first pivotal connection engages the linkageproximal portion and the engaging ring of the second pivotal connectionengages the linkage distal portion.
 2. The orthotic or prosthetic jointaccording to claim 1, wherein the bearing assembly of the first pivotalconnection further has a second mount at the linkage proximal enddefining a bore and receiving the engaging ring therein.
 3. The orthoticor prosthetic joint according to claim 2, wherein the bearing assemblyof the first pivotal connection further has: a plurality of retainerrings positioned within the second mount bore on either side of theengaging ring and retaining the engaging ring within the second mountbore.
 4. The orthotic or prosthetic joint according to claim 3, furthercomprising: a plurality of seals positioned within the second mount boreon either side of the retainer rings.
 5. The orthotic or prostheticjoint according to claim 2, wherein the second mount further has anextending portion that is mounted to the linkage proximal portion. 6.The orthotic or prosthetic joint according to claim 5, wherein thelinkage releasably engages the extending portion.
 7. The orthotic orprosthetic joint according to claim 1, further comprising a plurality ofseals each seal having at least one receiving portion and at least onesealing member received therein.
 8. The orthotic or prosthetic jointaccording to claim 7, wherein the at least one sealing member isresilient so as to retain its shape when in an unstressed condition. 9.The orthotic or prosthetic joint according to claim 1, wherein thelinkage is an active or passive control unit.
 10. The orthotic orprosthetic joint according to claim 1, wherein the first proximal mountfurther has a plurality of flange portions defining bores therethrough;wherein the cylindrical rod of the bearing assembly of the first pivotalconnection is fixedly received within the plurality of bores such thatthe linkage is free to rotate in three directions with respect to thefirst proximal mount.
 11. The orthotic or prosthetic joint according toclaim 1, wherein the frame further has a plurality of bores formedwithin a distal portion thereof; wherein the cylindrical rod of thebearing assembly of the second pivotal connection is received within theplurality of bores such that the linkage is free to rotate in threedirections with respect to the frame.
 12. The orthotic or prostheticjoint according to claim 1, wherein the first proximal mount and thedistal portion of the frame each define a plurality of borestherethrough for fixedly receiving the cylindrical rods of a bearingassembly of the first and second pivotal connections respectively, suchthat the linkage is free to rotate in three directions with respect toboth the first proximal mount and the frame, respectively.
 13. A bearingassembly adapted to be used as a joint connection, the bearing assemblycomprising: a frame having proximal and distal portions; a linkage; anengaging ring engaging a portion of the linkage; a swivel portiondefining a bore and received within the engaging ring so as to freelyrotate in at least three directions; and a cylindrical rod engaging thebore within the swivel portion and fixedly engaging the frame; whereinthe linkage is free from torsional loading and is free to rotate withthree degrees-of-freedom with respect to the frame.
 14. The bearingassembly according to claim 13, wherein the linkage has a mount defininga bore that receives the engaging ring in a fixed manner
 15. The bearingassembly according to claim 13, further comprising a plurality ofretainer rings positioned within the mount bore on either side of theengaging ring and retaining the engaging ring within the mount;
 16. Thebearing assembly according to claim 15 further comprising: a pluralityof seals positioned within the mount bore on either side of the retainerrings.
 17. The bearing assembly according to claim 14, wherein the mountfurther has an extending portion that is removably mounted with thelinkage.
 18. The bearing assembly according to claim 14, wherein theengaging ring engages a proximal portion of the linkage and the firstand second ends of the cylindrical rod engage the linkage in a fixedmanner.
 19. The bearing assembly according to claim 14, wherein thefirst and second ends of the cylindrical rod engage a distal portion ofthe frame and the engaging ring engages the linkage distal portion. 20.An orthotic or prosthetic joint comprising: a frame having proximal anddistal portions; a first proximal mount pivotally engaging the frame;and a linkage having proximal and distal portions, and a first pivotalconnection to the first proximal mount at the proximal portion thereof,and the linkage having a second pivotal connection to a distal portionof the frame at the distal portion thereof such that the linkage is freefrom torsional loading and rotates with three degrees-of-freedom withrespect to the frame; wherein the first and second pivotal connectionsof the linkage each include a bearing assembly having: an engaging ring;a swivel portion defining a bore and received within the engaging ringso as to freely rotate in at least three directions; and a cylindricalrod engaging the bore within the swivel portion; wherein first andsecond ends of the cylindrical rod of the first pivotal connectionengage the linkage in a fixed manner, first and second ends of thecylindrical rod of the second pivotal connection engage a distal portionof the frame.